Device for adjusting objectives of different focal lengths in cameras



May 28, 1946. H. BRETTHAUER 2,401,134 5 DEVICE FOR ADJUSTING OBJECTIVESOF DIFFERENT FOCAL LENGTHS- IN CAMERAS Filed Dec. 27, 1940 I 2Sheets-Sheet 1 HHHIIHHIHI ll IHIIHIHHIHI HermaflflBr-eZi/zauer May 28,1946. H. BRETTHAUER 2,401,134

7 DEVICE FOR ADJUSTING OBJECTIVES OF DIFFERENT FOCAL LENGTHS IN CAMERASFiled Dec. 27, 1940 2 Sheets-Sheet 2 a motion picture camera,

. view of a section through the mount carrier according to Fig. 1

Across onrncrrvn's room. innards DEVKCE FOR- DWFERENT ERAS 1 HermannApplication Bretthauer,

an m cfieriin liianirwita, Germany; vested in the Mien Property@ustodian December 2'3,

it iil, Serial lilo. 371,976 in Germany November 2%, with 2 Claims. (Ci.9H5) The invention relates to a device for merit of exchangeableobjectives of different focal lengths in cameras, specifically motionpicture cameras, in which the objective carrier is axially displaceablein accordance with the amount of turn of an adjusting member.

In order to confine to the use of one single distance scale whenadjusting objectives of different focal lengths, it has for instancebeenproposed to provide mounts for taking exchangeable objectives inwhich part of the axial movement of the objectives is carried out bymeans of an adjusting mechanism provided on the camera, while theremaining part of the axial displacement differing in length accordingto the respective objectives used is effected by a second adjustingmechanism connected with the objective.

In distinction therefrom the invention provides for the insertion insuch a device of a driving between the member controlling the axialmovement of the objective and the adjusting member of the mount, saiddriving mechathe action of adjustment radial slot s about the axis nismproducing a relative movement between said controlling and saidadjusting member. In this connection the controlling member may forinstance be supported eccentrically relative to the adjusting member andconnected to the adjusting member by a driver sliding in a guiding slot.

\ Contrary to the above mentioned known devices,

the device according to the invention is suitable for universal use andafiords various advantages the, part of objectives which is arranged onobjective itself is considerably simpler of construction and adjustment.

Two embodiments of the invention are represented in the drawings ofwhich Fig. 1 is a front view of the mount carrier of Fig. 2 a lateralFig. 3 a lateral view of an exchangeable ob,-

' jective in part section,

Fig. 4 a front view of a detail of the-objective represented in Fig. 3,

Fig. 5 a lateral view of a section through a mount carrier of anotherembodiment on a motion picture camera,

Fig. 6 a lateral view of an exchangeable objective in the secondembodiment in part section, and

' Fig. '1 is a longitudinal sectional view through the objective showninFig. 6.

Figs. 1' and cured on the camera for two coupled mounts. A gear wheelrim 2 is supported in the carrier i so as to be rotatable about an axisA-A. A lug 3 of the gear wheel rim 2 projects'through the wall or thecarrier I. This lug slides in a 2 represent a mount carrier i seof anadjustable ring 5 rotating B-B. The adjusting ring is supsleeve 6 of themount carrier i. A set ring l is secured on the sleeve in front of theadjusting ring 6. A bayonet-joint ring 8 is turnable on the inner sideof the sleeve b having a flange 2d held by a covering ring 9. A handle25 is arranged on the bayonet ring 8. A pin iii is disposed in a bore ofthe set ring which engages a recess in the adjusting ring 5 wheninfinite adjustment is called for. The flange M of the bayonet ring 8possesses a cor- (not shown) arranged in such manner that the pincannotescape into this recess nite position.

A driver pin ii is provided on the gear wheel at a rotation of theadjusting ring 5 is caused to follow by the lug 3. -As the gear wheelrim 2 is supported eccentrically relative to the adjusting ring 5, thelug 3 can slide in the radial groove 4. The gear wheel rim 2 engages ina gear wheel rim 26 serving to adjust a finder objective not shown.

The objective mount shown in Figs. 3 and 4 is inserted in the mountcarrier I in such manner that the bayonet sets i3, 30 provided on theouter tube i2 project through slots i4, 21, 28 in the bayonet ring 8 andare capable of being locked through a turn of the bayonet ring. Anobjective tube displaceable but nonrotatable in the mounting tube i2. Aworm threaded tube It is supported rotatably but not axiallydisplaceable in the mounting tube l2 and engages in the thread of theobjective tube l5, so that the latter H5) at a turn of the worm threadedtube I8 is axially displaced .by an amount corresponding to the threadascent covered. The worm threaded tube I6 is connected with aflange-like control ring l8 by means of grub screws i1, said controlring l8 possessing a guiding groove 29. A catch is is mounted in thecontrol ring l8, which, when the control ring I8 is set for infiniterotation, urged by the leaf spring 20 engages a slot 2| of the mountingtube J2. Thus, when the mount is removed from the mount carrier, thecontrol ring 18 is locked for infinite movement by means of the catchis. Upon insertion of the mount, the catch i9 is automatically removedfrom the slot 2i and thus thecontrol ring i8 is released. The driver pinll of the gear wheel rim 2 thereby engages in the guiding groove 29 ofthe control ring I8.

Through the locking of the control ring it on the and Ib in less than aone hand and of the adjusting ring 5 on the other hand, the guidinggroove 29 and the driver pin II are brought into correspondingpositions, when the mount is inserted. As will be readily apparent, thecontrol ring I8 and the gear wheel rim 2 are eccentric relative to oneanother. Now

if the gear wheel rim 2 is turned by means of the adjusting ring 5, thepin II of the control ring is caused to follow; whereby however thecontrol ring through the driver II sliding in the guiding groove 29makes a movement relative to the gear wheel rim 2 which is determined bythe position and the course of the guiding groove 29 and by the amountof eccentricity. It is practically always possible by means of suitabledimensioning of the worm acclivity and of the eccentricity to render thecourse of the guiding groove uncomplicated, i. e. either circular, as inthe embodiment, or rectilinear and consequently easy of manufacture. Bydisplacing the control ring I8 relative to the worm threaded-tube I6 itis possible to adjust the objective tube accurately for infiniteturning.

An adjusting scale 23 cooperating with a pointer 22 of the adjustingring 5 is calibrated in accordance with the finder objective controlledby the gear wheel rim 26. The finder objective might of course becontrolled in the usual simple manner by means of a worm threaded mount.In the embodiment, however, the gear wheel rim 26 is likewise eccentricrelative to the control ring of the worm threaded mount andcoupled withsame by means of a driver pin 3I sliding in a guiding groove. Thisconstruction has the advantage that the deviations from the desiredfocal length even in the finder objective may be taken into account bysuitable development of the guiding groove. A further possibility ofadaptation consists in choosing a different eccentricity for the finderobjective than that of the main objective. By giving the two gear wheelrims 2, 26 a different number of teeth, an additional means exists ofchanging and compensating for the transmission between focussing andadjustment. It is immaterial as regards the inventive principle whethermerely one single objective or a pair of coupled objectives or even, forinstance in a revolver arrangement, several coupled objectives areadjusted, in the case of the latter according to a common distance scaleor to the ascertained clearness of image revealed by one of the coupledobjectives.

In the second embodiment represented in Figs. 5, 6 and 7 the mount I00is capable of being screwed'by means of coarse pitch thread I 00acompleted revolution into a sleeve I06 of a mount carrier IN. A gearwheel rim I02 with a driver pin II I is turnable by means of anadjusting knob I05 via a gear wheel I0 4. The driver pin III is axiallyresilient. The mount I00 in its construction substantially correspondsto that described above with the exception that no locking arrangementis provided for the control ring I I8 relative to the objective tube H2;In other words, the objective mount H5 is axially movable relative toobjective tube, H2, whereas control ring H8 is rotatable relative to theobjective tube, said relative rotation being produced by the worm threadconnection II6. When the mount I00 is being screwed in, the resilientdriver pin IIIis in the first instance depressed, and in the course ofthe pin III and the gear screwing-in movement, snaps into the guidinggroove I 03 of the control ring II8. Hence upon continuation of thescrewing movement, the control ring H8 i retained by the driver I II andthe objective tube displaced axially so that upon termination of thescrewing movement the objective is automatically adjusted for thedistance corresponding to the position of the driver wheel rim I02,respectively. In this embodiment, therefore, the objective ma beexchanged at any adjustment and the new objective is automaticallyadjusted for the same sharpness as was the objective previously removed.In addition the looking arrangements for thehmount and the adjustmentmay be dispensed W1 What I claim is:

1. Device for the adjustment on cameras of exchangeable objectives ofdifierent focal lengths comprising in combination, a mount carriersecured on the camera and serving to take the respective objectivemounting tubes, said mount carrier having a rotatable first ring elementand a second rotatable ring element as well as means for causing thefollow-up movement of the second ring element on turning the first ringelement, said two ring elements being eccentrically supported relativeto one another, an objective carrier axially displaceable in theobjective mount tube, means for axially displacing the objective carrierin accordance With the turn of the second ring element, said means fordisplacing said second objective carrier consisting of a second, innertube provided with a worm thread seated in the objective mount tube andcooperating with the objective carrierand a control ring secured on theworm threaded tube and cooperating with the second ring element by meansof an oblique guide provided on said control ring, said oblique guideconsisting of a guiding slot in the control ring and a driver pinsecured on the second ring element and sliding in' the guiding slot.

2. Device for the adjustment on cameras of exchangeable objectives ofdifferent focal lengths, comprising in combination, a mount carriersecured on the camera and serving to take the respective objectivemounting tubes by means of a bayonet joint, said mount carrier having arotatable first ring element and a' second rotatable ring element aswell as means for causing the follow-up movement of the second ringelement on turning the first ring element, said two ring elements beingeccentrically supported relative to one another, an objective carrieraxially displaceable in the objective mount tube, means for axiallydisplacing the objective carrier in accordance with the turn of thesecond ring element,

said means for displacing said second objective carrier consisting of asecond, inner tube provided with a worm thread seated in the objectivemount tube and cooperating with the objective carrier and a control-ringsecured on the worm threaded tube and cooperating withthe second ringelement by means of an oblique guide provided on said control ring, saidoblique guide consisting of a guiding slot in the control ring and adriver pin secured on the second ring element and sliding in the guidingslot, said control ring being rotatable relative to the worm threadedtube with a view to adjustment and restrainable at the worm threadedtube.

c HERMANN BRETTHAUER.

